What survives is essentially a shaped absence: a low but prominent hillock rising two to five metres above surrounding rough pasture, marsh, and scrub, its oval summit carrying a shallow depression about eight metres across. The structure has been swallowed by the landscape rather than preserved by it, and what the eye reads as natural terrain turns out, on closer inspection, to be something considerably older.

The site is classed as a probable rath, the Irish term for a ringfort, the circular or oval earthwork enclosures built across Ireland from the early medieval period onward, typically as enclosed farmsteads for a single family or small community. At Ballytarsna, no surface traces of the enclosing bank survive, but the hillock itself measures roughly 28 metres along its longer axis and is encircled by a broad band of rushes and reeds, ten to fifteen metres wide. That dense ring of wetland vegetation is likely evidence of an infilled outer fosse, the defensive ditch that would once have encircled the settlement. The hillock's commanding position offers extensive views across the surrounding low ground, broken only by higher ground to the north-north-east, which is precisely the kind of site early medieval communities favoured. Ordnance Survey maps add a further detail: both the first edition of 1842 and the later Cassini edition of 1920 recorded the site under its current name and noted a natural spring approximately ten metres to the north of the monument, a resource that would have made the location practical as well as defensible.

The hillock's south-eastern edge shows signs of disturbance, part of the overgrown slope having been dug away at some point, and the summit depression is partly obscured by vegetation at its eastern end. These small erasures, accumulated over centuries, mean the site rewards careful attention rather than a quick glance from the field margin.